Leetcode513. Find the value in the lower left corner of the tree

Their thinking ：
The value required by the title must be on the last level , That's for sure . So we just need to find the nodes of the last layer . Then we can do something .

So for such a tree , Let's go through the sequence , In fact, you can traverse from the right subtree of the tree , Then traverse the left subtree , So let's queue up for the last element , It is the leftmost element of the deepest layer we are looking for .
Do you feel , For this question , Breadth first algorithm , Easier and more suitable for

The code is as follows :

class Solution {
    
    public int findBottomLeftValue(TreeNode root) {
    
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while(!queue.isEmpty()){
    
            root = queue.poll();
            if (root.right != null) queue.offer(root.right);
            if (root.left != null) queue.offer(root.left);
        }
        return root.val;
    }
}